1. Technical Field
The present disclosure relates to an electronic apparatus having an antenna.
2. Related Art
In an electronic apparatus that performs mobile communication and reception of GPS radio waves, by using a satellite, it is preferable to use a circularly polarized wave antenna in order to reduce the reception sensitivity variation caused by a change in a polarization plane due to a change in the orientation of the antenna, or to improve the theoretical sensitivity by corresponding circularly polarized waves. For example, a technology is disclosed in which a ring antenna including an element with power feeding and a C-shaped element without power feeding formed on the surface of the dielectric is mounted on an electronic timepiece, as a circularly polarized wave antenna (for example, JP-A-2013-214940).
To make the ring antenna to function as a loop antenna, an antenna length of 1λ is theoretically required, but in JP-A-2013-214940, a wavelength shortening effect is achieved by using a dielectric and the actual antenna length is configured to be shorter than 1λ.
However, since the ring antenna uses a dielectric, the occupied volume of the antenna is large, and in the case where the antenna is built into an outer case, a timepiece becomes large. Therefore, depending on the type of timepiece, it is difficult to adopt the ring antenna.
Further, in the case of a thin timepiece, since a distance from the feeding point of the antenna to an element without power feeding is reduced, antenna performance is reduced even when employing the ring antenna.
Although it is conceivable to attach the ring antenna to the outer case, in this case, a conduction structure of the circuit board and the antenna is required. In addition, it also requires waterproofing measures for the conduction structure, and thus the structure becomes complicated or the cost is increased.
As an antenna used in an electronic timepiece, there is a patch type antenna in addition to the ring antenna. However, since this antenna also uses the dielectric, the occupied volume of the antenna is large. As a result, when the antenna is incorporated in the outer case similar to the ring antenna, there are constraints on a component layout, and it is not suitable for miniaturization and thinning of the timepiece. When the antenna is disposed in the outside of the outer case, the patch antenna is designed to be projected from the case, and the degree of freedom in design is smaller than the ring antenna.